JP3198148B2 - Hydraulic powder composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic powder composition obtained from asbestos cement product waste.

[0002]

2. Description of the Related Art In recent years, the disposal of general industrial waste is becoming an international problem. In particular, since the problem of asbestos health has become a social issue, the disposal of asbestos-containing products, especially asbestos cement products for building materials, has been increasing. Is getting harder. As a conventional method of treating asbestos cement product waste, a method of packing in a double bag and burying the asbestos at a depth of 2 meters or more in the soil so as to prevent scattering of asbestos has been adopted. However, it is expected that this method will become more and more difficult as landfills become increasingly remote.

[0003] Under such circumstances, several methods for treating asbestos have been proposed. For example, JP-A-3-30885 discloses that asbestos is mixed with a dewatered cake of water-treated sludge, the mixture is formed, and the formed mixture is supplied to a high-temperature hearth made of a carbon-based combustible material and heated. A method for melting asbestos to melt is disclosed. Japanese Patent Application Laid-Open No. 3-60789 discloses that natural asbestos is
Water-treated sludge having a higher content of CaO than O ₂ is mixed as a basicity adjuster and binder, the mixture is molded, and the molded mixture is supplied to a high-temperature hearth made of a carbon-based combustible material and heated. A method for melting asbestos to melt is disclosed. These treatment methods can detoxify asbestos and form a form free of secondary pollution.

Further, Japanese Patent Application Laid-Open No. Hei 3-4980 discloses that asbestos and a carbon-based solid fuel are mainly used, a binder and / or an oxidizing agent are added as required, and the asbestos is further reduced in melting point if desired. A basic inorganic solid is added and mixed, the resulting mixture is granulated, and the mixture is burned while blowing air to melt and sinter the asbestos-like asbestos. A chemical treatment method is disclosed.

Japanese Patent Application Laid-Open No. 3-21387 discloses that asbestos is treated with phosphoric acid and calcined, and further, an alkali agent such as calcium carbonate or calcium hydroxide is added thereto and calcined. A method for detoxifying waste asbestos, characterized by the following, is disclosed. According to this method,
It is disclosed that asbestos waste such as packing made of asbestos can be rendered harmless and used as fertilizers.

Japanese Patent Application Laid-Open No. 60-186422 discloses that a dissolution promoter is added to asbestos,
The method of vitrifying asbestos waste by thermal decomposition is disclosed above. Further, JP-A-62-2379
No. 84 discloses that asbestos-containing waste is mixed with a melting aid, and if necessary, additives such as a melting accelerator are added, followed by high-temperature heating in a melting furnace to convert the asbestos fiber into glass. A method for disposing of asbestos-containing materials, which comprises converting into a substance having a crystal structure other than asbestos, is disclosed. Japanese Unexamined Patent Publication No. 2-303585 discloses that municipal waste incineration ash discharged from municipal waste incinerator and asbestos material are mixed to form a material to be melted, and the material to be melted is melted in a surface melting furnace. In addition, there is disclosed an asbestos melting method characterized by forming asbestos material into molten slag together with municipal waste incineration ash.

[0007]

Most of the asbestos treatment methods disclosed in the above-mentioned publications vitrify asbestos at a high temperature to render it harmless, and the harmless treated material is discarded. Most, and in some cases, the use of treated materials as fertilizers has been proposed, but no method has been proposed to effectively recycle asbestos cement waste.

Accordingly, an object of the present invention is to detoxify asbestos without disposing of asbestos cement product waste,
Another object of the present invention is to provide a hydraulic powder composition that can be reused.

[0009]

That is, the hydraulic powder composition according to the present invention provides an asbestos cement product of 600 to 1450.
Features ℃ temperature, a heat-treated product of the asbestos cement products were heated for 15 minutes to 2 hours, the peak of asbestos by X-ray diffraction Ri absence der, and glassy solidified product is an absence der Rukoto And

[0010]

Since the asbestos contained in the asbestos cement product is a fibrous hydrated silicate mineral, its crystal structure is decomposed by the dehydration phenomenon due to the high temperature treatment. The asbestos contained in the asbestos cement products is usually chrysotile and / or amosite. Chrysotile dehydrates at a temperature of about 600 ° C. FIG. 1 is an X-ray diffraction diagram showing the thermal decomposition of chrysotile, and it can be seen that it is completely decomposed and non-crystallized at a temperature of 700 ° C. Further heating to 900 ° C. produces non-asbestos forsterite, which is harmless. Further, when the temperature is increased, it is uneconomical in terms of thermal energy, and when the temperature is increased to the sintering temperature, it solidifies into a glass. Amosite also begins to dehydrate at 600 ° C. and collapses at 900 ° C. to become another substance.

Therefore, the hydraulic powder composition according to the present invention is obtained by heating and detoxifying asbestos cement product waste. By this heat treatment, the asbestos in the asbestos cement product is dehydrated, and as a result, the crystalline structure can be destroyed and converted to another substance other than asbestos. Further, the binder in the asbestos cement product is thermally decomposed by this heat treatment, and can be converted into a substance having hydraulic properties. Here, the hydraulic property refers to the property of causing a hydration reaction and hardening when water is added. The mechanism why the hydraulic property is re-expressed by the heat treatment is not yet known.
That is, the hydraulic powder composition of the present invention is hardened by simply adding water and kneading, and the composition of the present invention is added with other components such as reinforcing fibers and cement, kneaded, and further,
It is also cured by the addition of water, and can effectively recycle asbestos cement product waste.

[0012] The heat treatment of the asbestos cement product which is performed when the hydraulic powder composition of the present invention is produced is 600 to 145
It is desirable to carry out within a range of 0 ° C. If this treatment temperature is below the lower limit, the asbestos can not be detoxified, and if it exceeds the upper limit, it is solidified into a glass as described above, and if it is treated in a powder state, it is dispersed and molded. Hydration (hydraulic) is also lost, and molding and hardening cannot be performed in the steps described below.

The heating and detoxification treatment of asbestos cement product waste may be carried out after the waste has been pulverized in advance, or the particle size may be adjusted by carrying out the pulverization after treating the waste as it is. The heating and detoxification time is usually 15 minutes to 2 minutes.
The processing time may be relatively short if the processing temperature is high, and the processing time may be relatively long if the processing temperature is low.

The hydraulic powder composition of the present invention which has been subjected to the heating and detoxifying treatment as described above has hydraulic properties, and is obtained by adding a predetermined amount of water to the composition of the present invention, press forming and curing. Then, a cured molded body can be obtained. The amount of water added to the composition of the present invention varies depending on the pressure molding method to be applied. In the case of press molding provided with a dehydration mechanism, the weight ratio of water / solid content is about 2 to 10 In the case where the dehydration mechanism is not provided, the weight ratio is about 0.2 to 2. A mixture of the composition of the present invention and water at such a ratio is filled in a mold having a predetermined shape, molded under pressure, and if a dehydration mechanism is provided, excess water is dehydrated to obtain a molded article. Is taken out and cured to obtain a cured molded body.

Further, the paper can be formed using a wet machine usually used for the production of asbestos cement products. In this case, the green sheet is pressure-formed by a making roll of a wet machine. Further, the green sheet thus formed can be re-pressed by a press. The papermaking operation may be performed under conventional conditions, and no special operation is required. Also, an extrusion molding method can be used.

The hydraulic powder composition of the present invention may further contain reinforcing fibers such as cellulose fibers, polyvinyl alcohol fibers or wollastonite, or cement. The addition of reinforcing fibers to asbestos cement products is a conventional means for increasing strength and improving drainage, and the amount of addition is up to about 10% by weight based on the composition of the present invention. Further, if cement is added, the strength can be increased. The amount of cement added is up to about 70% by weight based on the composition of the present invention. The addition of the reinforcing fiber or cement does not affect the subsequent molding operation or the like.

[0017]

【Example】

Example 1 The asbestos cement board (JIS A5403: flexible board) was roughly divided by a jaw crusher, then ground by a hammer mill, and pulverized by a Nara free grinding machine. Sieve size Particle size distribution (%) 8 mesh 0 24 mesh 11.0 32 mesh 10.8 60 mesh 19.4 100 mesh 12.4 PAN 46.4 Heat treatment of the above powder at 1000 ° C. for 30 minutes did. When the powder composition after the treatment was measured by X-ray diffraction, no chrysotile peak was observed, and it was confirmed that the powder composition was detoxified by heat decomposition.

Next, 30% of water is added to the above-mentioned powder composition, kneaded, press-molded to a size of 150 mm × 80 mm × 10 mm, and placed in a humidity box (100% relative humidity).
° C) for 16 hours, and then dried at 105 ° C for 24 hours. The density of the obtained cured molded article is 1.68 kg / c.
m ³ and flexural strength were 53.7 kg / cm ² , confirming that the composition of the present invention has hydraulic properties.

Reference Example 1 A cured molded article was obtained by performing the same operation as in Example 1 except that pulp of 5% by weight was added to the above powder composition. The density of the obtained cured molded article is 1.42 kg / c.
m ³ , and the flexural strength was 61.8 kg / cm ² .

Reference Example 2 Pulp of 5% by weight based on the above powder composition and 20%
A cured molded article was obtained by performing the same operation as in Example 1 except that the cement was added by weight%. The density of the obtained cured molded product was 1.51 kg / cm ³ , and the flexural strength was 97.2.
kg / cm ² .

Example 2 A corrugated asbestos slate was roughly divided with a jaw crusher, then ground with a hammer mill, and pulverized with a Nara free pulverizer. The powder had the following particle size: Sieve Mesh size Particle size distribution (%) 8 mesh 0 24 mesh 7.2 32 mesh 7.7 60 mesh 19.7 100 mesh 13.1 PAN 52.3 The powder composition was heat-treated at 1000 ° C. for 30 minutes.
When the powder after the treatment was measured by X-ray diffraction, no chrysotile peak was observed, and it was confirmed that the powder was decomposed by heating and made harmless.

Next, 30% of water is added to the above powder composition, kneaded, press-molded to a size of 150 mm × 80 mm × 10 mm, and then placed in a humidity box with a relative humidity of 100% (50%).
° C) for 16 hours, and then dried at 105 ° C for 24 hours. The density of the obtained cured molded product is 1.62 kg / c.
m ³ and flexural strength were 51.8 kg / cm ² , confirming that the composition of the present invention has hydraulic properties.

REFERENCE EXAMPLE 3 Next, 5% by weight of pulp,
% Of cement was added, and 30%
% Water, kneaded, 150 mm x 80 mm x 10 m
After press molding to a size of m, in a humidity box with 100% relative humidity
Cured at (50 ° C.) for 16 hours and then dried at 105 ° C. for 24 hours. The density of the obtained cured molded article is 1.58 kg /
cm ³ , and the flexural strength was 102.1 kg / cm ² .

Example 3 100% asbestos cement board (JIS A5403: flexible board)
Heat treatment was performed at 0 ° C. for 30 minutes. Thereafter, the mixture was roughly divided with a jaw crusher, then ground with a hammer mill, and pulverized with a Nara free grinding machine. When the powder composition after the treatment was measured by X-ray diffraction, no chrysotile peak was observed, and it was confirmed that the powder composition was detoxified by heat decomposition.

Next, 30% of water is added to the above powder composition, kneaded, press-molded to a size of 150 mm × 80 mm × 10 mm, and then placed in a humidity box of 100% relative humidity (50%).
° C) for 16 hours, and then dried at 105 ° C for 24 hours. The density of the obtained cured molded article is 1.56 kg / c.
m ³ and flexural strength were 57.6 kg / cm ² , confirming that the composition of the present invention has hydraulic properties.

The hydraulic powder composition according to the present invention is obtained by detoxifying asbestos cement product waste by heating.
Asbestos cement products that could only be disposed of by burial or the like can be effectively recycled, and the effect is extremely large. In addition, the hydraulic powder composition according to the present invention can be replaced with a part of ordinary raw materials when producing ordinary asbestos cement or non-asbestos fiber cement board.

[Brief description of the drawings]

FIG. 1: 700 ° C. and 900 ° C. before chrysotile heating
FIG. 6 is an X-ray diffraction diagram after heat treatment in FIG.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B09B 3/00

Claims (1)

(57) [Claims] 1. An asbestos cement product having a temperature of 600 to 1450 ° C.
At a temperature, a heat-treated product of the asbestos cement products were heated for 15 minutes to 2 hours, the peak of asbestos by X-ray diffraction Ri absence der, and glassy solidified product and the said absence der Rukoto Hydraulic powder composition.